One-third of cadaveric renal allografts is shipped between organ procurement organizations (OPOs). Movement of allografts occurs due to national sharing of HLA-matched kidneys, subsequent payback of organs, and arrangements between individual OPOs. Shipment can impact allograft survival via the level of HLA matching and the duration of cold ischemia time (CIT). Shipment and increased CIT may augment allograft immunogenicity and increase rates of acute rejection (AR). The specific aims of this study are to examine the associations between CIT and AR, and between organ shipment and AR, in cadaveric renal allografts during the first 12 months after transplantation. Dr. Harold I. Feldman is the sponsor of this fellowship application and is the principal investigator of an ongoing NIH-sponsored, multicenter, prospective cohort study of drug compliance, race, and renal allograft survival, which has enrolled over 850 patients. We propose to analyze patient-level data from this study to examine the independent association of CIT and AR using multivariate Cox proportional hazard models. Linear and non-linear effects of CIT will be explored. In a similar modeling strategy, the independent association between allograft shipment and AR will be examined. Duration of CIT, and slow or delayed allograft function will be explored as potential mechanisms that explain any association observed between shipment and AR.